Orcas, commonly called killer whales, are known to be ferocious apex predators — but scientists were left scratching their heads after one orca whale was recorded seemingly caring for a long-finned pilot whale calf.
Researchers spotted the abnormal pair off the western coast of Iceland in August 2021.
In a recently released paper in the Canadian Journal of Zoology, scientists said the emaciated pilot whale calf was observed alongside an adult female orca whale, called SN0540, or Sædís. For 21 minutes, the scientific team observed the pair travelling together with two other adult orcas, a male called Zale and a female named Dragonfly.
There were no other pilot whales nearby.
The paper claims Sædís was not producing milk and was therefore unable to feed the pilot whale calf. The calf was not observed interacting with the other members of the orca pod.
Though there is evidence to suggest orca whales occasionally prey on pilot whales, experts believe Sædís and the pilot whale calf may have displayed the first-ever recorded instance of interspecies care, called alloparenting, in orca whales.
However, scientists cannot definitively rule out whether the adopted pilot whale was taken in after it was orphaned — or if was a kidnapped to-go meal.
Killer whales are known to be emotionally intelligent animals, capable of displaying personality traits similar to humans, such as affection and playfulness. For this reason, experts believe alloparenting is a possible conclusion.
The orca and pilot whale were observed in “echelon formation,” a nurturing behaviour which sees the calf tucked close to the orca’s body as they swim. The formation allows the calf to “draft” alongside the larger whale and conserve energy at the expense of the parent’s own energy budget and foraging efficiency.
Sædís and her pod have been regularly observed since 2012, but she has never had her own offspring in that time frame. In the Journal of Zoology paper, experts hypothesize (without substantiated evidence) that Sædís may have miscarried or lost a newborn of her own and began caring for the pilot whale as a result.
The pilot whale calf has not been observed with Sædís since it was first seen in 2021. Given its emaciated state, experts believe the calf died. Sædís, Zale and Dragonfly still travel together.
Though this is the first known instance of orca alloparenting, other species have occasionally displayed the behaviour. In 2019, a bottlenose dolphin in coastal waters off French Polynesia was seen raising a melon-headed whale. On land, other groups like capuchin monkeys have been recorded caring for a baby marmoset.